From 2569f51471e53f6b18ee2ae6156fd82e37fd8576 Mon Sep 17 00:00:00 2001
From: Oleksandr Tymoshenko <gonzo@FreeBSD.org>
Date: Fri, 22 May 2015 02:00:44 +0000
Subject: [PATCH] Add helper method fdt_find_child to make access to child
 nodes easier.

Some FDT nodes have complex properties organized as a child sub-nodes
(e.g. timing for LCD panel) we need easy way to obtain handles for
these sub-nodes
---
 sys/dev/fdt/fdt_common.c | 17 +++++++++++++++++
 sys/dev/fdt/fdt_common.h |  1 +
 2 files changed, 18 insertions(+)

diff --git a/sys/dev/fdt/fdt_common.c b/sys/dev/fdt/fdt_common.c
index f00519e5646f..0198d550ca2c 100644
--- a/sys/dev/fdt/fdt_common.c
+++ b/sys/dev/fdt/fdt_common.c
@@ -57,6 +57,7 @@ __FBSDID("$FreeBSD$");
 
 #define FDT_COMPAT_LEN	255
 #define FDT_TYPE_LEN	64
+#define FDT_NAME_LEN	32
 
 #define FDT_REG_CELLS	4
 
@@ -309,6 +310,22 @@ fdt_find_compatible(phandle_t start, const char *compat, int strict)
 	return (0);
 }
 
+phandle_t
+fdt_find_child(phandle_t start, const char *child_name)
+{
+	char name[FDT_NAME_LEN];
+	phandle_t child;
+
+	for (child = OF_child(start); child != 0; child = OF_peer(child)) {
+		if (OF_getprop(child, "name", name, sizeof(name)) <= 0)
+			continue;
+		if (strcmp(name, child_name) == 0)
+			return (child);
+	}
+
+	return (0);
+}
+
 phandle_t
 fdt_depth_search_compatible(phandle_t start, const char *compat, int strict)
 {
diff --git a/sys/dev/fdt/fdt_common.h b/sys/dev/fdt/fdt_common.h
index 3d05341dad1d..68012978ac26 100644
--- a/sys/dev/fdt/fdt_common.h
+++ b/sys/dev/fdt/fdt_common.h
@@ -81,6 +81,7 @@ u_long fdt_data_get(void *, int);
 int fdt_data_to_res(pcell_t *, int, int, u_long *, u_long *);
 phandle_t fdt_find_compatible(phandle_t, const char *, int);
 phandle_t fdt_depth_search_compatible(phandle_t, const char *, int);
+phandle_t fdt_find_child(phandle_t, const char *);
 int fdt_get_mem_regions(struct mem_region *, int *, uint32_t *);
 int fdt_get_reserved_regions(struct mem_region *, int *);
 int fdt_get_phyaddr(phandle_t, device_t, int *, void **);